Pressurized dispensing containers are used for dispensing a wide variety of products from mobile to viscous liquid products, powdered products and the like and typically employ a liquid propellant such as a hydrocarbon or fluocarbon having sufficiently high vapor pressure at normal working temperatures to propel the product through the dispensing apparatus. These are commonly used for dispensing pharmaceuticals and medicaments.
Generally such pressurized dispensing containers comprise a container, a dispensing valve and a closure which is crimped to the container to hold the valve in place. A seal, usually made of an elastomeric material, is compressed between the container and the closure to prevent leakage. The efficiency of the sealing arrangement is particularly important to prevent the leakage of propellants. It is important that leakage is minimized, despite the latest propellants being more environmentally friendly than predecessors, to prevent the loss of the container contents, ensuring that there are sufficient contents available after storage to meet the claims of the packaging and also to ensure that the ratio of propellant to product remains constant.
It has hitherto been a problem that the deformation of the seal during the crimping operation can lead to a reduction in the effectiveness of the seal. During the crimping operation, the seal may also be deformed in a manner which does not provide a true seal.
Also it has hitherto been a problem that the permeability of the seal material with respect to the propellants has led to loss of propellant during storage of the container and during the shelf-life of the product.
To overcome such problems it has been proposed to use two seals, both of which are sandwiched between the container and the closure. An example of such proposal is described in International patent specification WO94/25373 in which is disclosed a pressurized dispensing container comprising valve means, a valve body, an open ended container body, a closure, a first seal between the container body and the closure and a second seal between the valve body and the container, said seals being independent such that the second seal seals off the container body from the first seal.
It is an object of the present invention to provide a further improved sealing arrangement for pressurized dispensing containers.